The present invention relates generally to molecular electronics, and more particularly to a molecular layer formed by Langmuir-Blodgett (LB) and self-assembling monolayer (SAM) methods.
Molecular devices comprising two electrodes (for example, a bottom electrode and a top electrode) and a molecular switching layer or film at the junction of the two electrodes are known. Such devices may be useful, for example, in the fabrication of devices based on electrical switching, such as molecular wire crossbar interconnects for signal routing and communications, molecular wire crossbar memory, molecular wire crossbar logic employing programmable logic arrays, multiplexers or demultiplexers for molecular wire crossbar networks, molecular wire transistors, and the like. Such devices may further be useful, for example, in the fabrication of devices based on optical switching, such as displays, electronic books, rewritable media, electrically tunable optical lenses, electrically controlled tinting for windows and mirrors, optical crossbar switches (for example, for routing signals from one of many incoming channels to one of many outgoing channels), and the like.
Typically, the molecular switching layer or film comprises an organic molecule that, in the presence of an electrical (E) field, switches between two or more energetic states, such as by an electrochemical oxidation or reduction (redox) reaction or by a change in the band gap of the molecule induced by the applied E-field.
It is important to form a good electrical contact between the electrode and the molecular switching layer in order to fabricate operative molecular devices. Molecules with special chemical end groups are able to form direct chemical bonds with metal or semiconductor electrodes to form a self-assembled monolayer (SAM), which may have a good electrical contact with an electrode(s). However, this self-assembled molecular layer formed on the surface of the electrode may generally be prone to a high density of defects. If a second electrode is formed on the molecular layer, then an electrical short may occur between the first and second electrode through the defects in the self-assembled molecular layer.
The formation of Langmuir-Blodgett (LB) layers or films employing switching molecules has been attempted because such layers or films are generally much denser than SAM films. Further, LB layers or films have relatively low defect densities compared to SAM films. However, it has proven to be a significant challenge to effectively bond LB films to the electrode substrate. As such, if the LB film is not sufficiently bonded to the electrode(s), then poor electrical contact may result.
As such, there is a need for providing a high density molecular switching layer on an electrode(s), which layer also bonds well with the electrode. Further, there is a need for reducing or substantially eliminating the electrical short circuit problems potentially associated with molecular electronic devices.